The 2009 Mercedes-Benz CLK550 is a sophisticated grand tourer powered by a 5.5-liter V8 engine (Engine Code 273.967 7) that demands precision and high-quality maintenance to remain in peak condition. Because this vehicle was designed for performance driving and rigorous use, standard mineral oils are often insufficient to handle the extreme thermal loads and high-revving nature of the engine. Proper lubrication is not merely about keeping parts moving; it is about protecting critical components from wear, maintaining oil pressure, and ensuring consistent power delivery. When choosing fluids for this vehicle, selecting products specifically engineered for European performance standards is essential for longevity and reliability.
Recommended AMSOIL Products
AMSOIL offers a comprehensive range of synthetic lubricants tailored to meet the specific engineering requirements of the 2009 CLK550. The following products are recommended to provide maximum protection for the engine, transmission, and cooling systems.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A specialized formula designed for the unique demands of European gasoline, diesel, and hybrid vehicles, featuring a precise blend of synthetic base oils and premium additives.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An excellent alternative for extreme temperature performance, offering the same European-specific protection with enhanced low-temperature flow characteristics.
- AMSOIL Oil Filter – Provides 99% filtration efficiency at 20 microns to keep engine parts lubricated and reduces wear by capturing wear-causing contaminants more effectively than competing filters.
- WIX Oil Filter – A premium aftermarket option that offers improvements over original equipment manufacturer-branded filters through superior media technology.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A phosphate-, nitrate-, and silicate-free formulation that protects cooling system metals, gaskets, and hoses up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option for those preferring to mix their own coolant, offering protection up to 1,000,000 miles in heavy-duty applications and exceeding standards for metallic corrosion.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Specifically formulated for the Mercedes-Benz 722.9 transmission, withstanding heavy towing, elevated temperatures, and challenging terrain while remaining fluid in sub-zero conditions.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective option that provides essential protection against wear for the automatic transmission without compromising on synthetic performance.
Engine Oil and Filter Specifications
The heart of the 2009 CLK550 is its 5.5-liter naturally aspirated V8, which requires a lubricant that can maintain viscosity and film strength under significant heat. The engine oil capacity is 9.0 quarts when the filter is included. It is crucial to note that after refilling the oil, the level must be checked to ensure proper operation. For optimal performance, AMSOIL recommends using either the 5W-40 FS or the 0W-40 FS European Motor Oils. Both formulations are engineered with a precise blend of synthetic base oils and premium additives designed to meet the stringent requirements of European vehicles.
The 5W-40 FS is an excellent choice for general European driving conditions, while the 0W-40 FS provides superior flow in colder climates without sacrificing protection at high temperatures. Both oils are compatible with the vehicle’s engine design and will help extend the time between service intervals while maintaining engine cleanliness. For filtration, the AMSOIL Oil Filter (Code EA15K39-EA) is a standout choice, offering extended service life and superior filtering efficiency compared to standard filters. Alternatively, the WIX Oil Filter (Code 57078-EA) provides a high-quality filtration solution with premium media that outperforms many OEM-branded filters, ensuring that contaminants are removed efficiently to keep the engine running smoothly.
Transmission and Cooling System Maintenance
While the engine is the primary concern, the automatic transmission in the 2009 CLK550, specifically the 722.9 series, requires precise fluid specifications to ensure smooth shifting and longevity. If your vehicle does not have the reduced-friction code A89, the total fill capacity for the 7-speed transmission is 9.5 quarts. Using a fluid that can withstand the rigors of heavy use is critical. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid (Code ATLPK-EA) is designed to remain fluid in sub-zero temperatures and provides reserve protection during heavy use or towing. It is compatible with the 722.9 transmission requirements and helps protect against wear and sludge buildup.
For those seeking a cost-effective solution that still delivers synthetic performance, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid (Code OTLQT-EA) is a recommended alternative. In the cooling system, the 2009 CLK550 holds 9.7 quarts of coolant. Maintaining the proper antifreeze mixture is vital to prevent corrosion and overheating. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a ready-to-use, 50/50 pre-mix formulation that protects all cooling system metals, gaskets, and hoses. It is free of phosphates, nitrates, and silicates, making it compatible with all other antifreeze colors and safe for the long-term health of the cooling system. For those who prefer to mix their own, the concentrated AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers extended protection and is suitable for both passenger cars and light trucks.
Why Proper Lubrication Matters for the CLK550
Owners of the CLK550 often drive this vehicle with a passion for performance, whether navigating city streets or enjoying open highways. The high-output 5.5L engine generates significant heat and mechanical stress, making standard lubrication insufficient for long-term reliability. Synthetic motor oils like the FS European Motor Oils provide a robust film of protection that resists breakdown under extreme thermal conditions. This ensures that critical components such as camshafts, bearings, and piston rings are shielded from wear, even during spirited driving or towing scenarios. Furthermore, high-quality synthetic transmission fluids maintain their viscosity better than conventional fluids, ensuring consistent shift quality and protecting the complex internal valves of the 7-speed automatic transmission.
Proper maintenance also extends to the cooling system, which plays a critical role in managing engine temperature. The specialized poly-organic acid (OAT) formulation in the recommended antifreeze ensures that corrosion inhibitors remain effective over long periods, preventing leaks and blockages that could lead to catastrophic engine failure. By using the correct AMSOIL products, owners can rest assured that their vehicle is protected against the full range of operating conditions, from freezing winters to hot summer drives, ultimately preserving the value and performance of this classic German sports coupe.
About the 2009 Mercedes-Benz CLK550
The 2009 Mercedes-Benz CLK550 represents the pinnacle of the brand’s grand touring legacy, blending luxury, performance, and everyday usability. Part of the W209 chassis generation, this model was produced from 2003 to 2009 and served as the convertible and coupe equivalent to the W211 E-Class sedan, sharing much of its platform architecture. Under the hood lies the naturally aspirated 5.5-liter V8 engine, known for its smooth power delivery, linear torque curve, and distinctive exhaust note. This engine code, 273.967, is renowned for its robustness and ability to rev freely, offering a driving experience that feels more engaging than the turbocharged engines that would later dominate the market.
This vehicle was highly regarded for its balanced handling characteristics, supported by a sophisticated multi-link suspension system that provided a comfortable ride while retaining sporty dynamics. The CLK550 appealed to enthusiasts who wanted the prestige and refinement of a Mercedes-Benz without sacrificing the joy of driving. It occupied a unique market position as a “soft-top” sports coupe that could comfortably seat four adults while providing a spirited driving experience. The model is celebrated for its timeless design cues, high-quality interior materials, and the engineering excellence that defined Mercedes-Benz in the early 21st century. Whether used as a daily driver or a weekend cruiser, the CLK550 remains a beloved classic that rewards owners who prioritize meticulous maintenance and high-performance lubrication.